1. Field of the Invention
The present invention relates to an image recording/reproducing apparatus which stores and reproduces digital images that are captured by an image input device, such as a digital still camera, an image scanner or a video camera.
2. Description of the Related Art
The development and manufacture of digital cameras in the field become remarkable in these years. In order to view an original image, which was obtained, with an image input device, such as a digital still camera, it was necessary to store the original image data in a memory device of a personal computer prior to the viewing. Hereinafter, such image data captured by the image input device will be called the original image data.
Generally, image reproduction and manipulation for the original image data are performed on a personal computer by using the original image data stored. The image data, produced by the image manipulation or the like, are usually loaded to or recorded in a storage device of the computer, such as a hard disk.
A data format of the original image data and an initial resolution thereof are not always fitted to a display monitor, such as a CRT. In order to allow the displaying and image manipulation of the original image data as well as the storage of manipulated image data, it is necessary to transform the original image with the initial resolution into a processed image signal with a secondary resolution that is fitted to the display monitor.
A digital still camera is typically provided with an internal memory that stores a small amount of the original image data obtained with the digital still camera. However, the capacity of the internal memory of the digital still camera is limited, and a conventional electronic album system is used with the digital still camera to store a large amount of the original image data. The conventional electronic album system typically employs a hard disk of a personal computer as the storage device that stores the original image data.
FIG. 3 is a diagram for explaining an image displaying procedure which is performed by an electronic album system.
As described above, the conventional electronic album system uses a hard disk of a personal computer to store the original image data which was obtained with the digital still camera. The original image data is stored in the hard disk of the computer and the stored image data is used for displaying images on a display monitor of the computer. At a start of an image displaying procedure performed by the conventional electronic album system, for example, a plurality of album items are displayed as an initial image-display screen on the monitor, based on the original image data stored in the hard disk.
During the image displaying procedure shown in FIG. 3, if an operator wishes to view one of the album items within the initial image-display screen on the monitor, the operator selects or clicks the desired one of the album items. This will cause a plurality of thumbnails of digital images, corresponding to the selected album item, to be displayed as a secondary image-display screen on the monitor. Further, if the operator selects or clicks one of the thumbnails, a detailed, enlarged digital image corresponding to the selected thumbnail, will be displayed as a final image-display screen on the monitor.
The conventional electronic album system requires image data processing based on the original image data every time the image-display screen is changed from one to another, in order to display one of the album items, thumbnails or digital images in a proper manner. The image data processing is a complicated task that is difficult to accomplish it at any time, and the time needed for completion of the image data processing for each screen change tends to be longer. In a certain case, the computer hangs up during the image displaying procedure, so that the image is not displayed in a proper manner.
As described above, in order to allow the displaying and manipulation of the original image data, it is necessary to transform the original image data with the initial resolution into a processed image signal with a secondary resolution. For example, when a plurality of thumbnails of digital images are displayed, the above electronic album system has to perform image compression of the original image data into a smaller size. When a detailed, enlarged digital image corresponding to the selected thumbnail is displayed, the above electronic album system has to transform the original image data with the initial resolution into the processed image signal with the secondary resolution that is fitted to the display monitor.
Typical resolutions of original image data obtained by digital still cameras are: 320 by 240 pixels, 640 by 480 pixels, 768 by 480 pixels, 1280 by 960 pixels, etc. A typical resolution of the VGA (video graphics array), widely used in personal computers, is 640 by 480 pixels. In the case of the above electronic album system, if an original image with the low resolution of 320 by 240 pixels were displayed directly on the display monitor, only one fourth of the image-display screen on the monitor is used to display the image. Further, in the case of the above electronic album system, if an original image with a high resolution of 768 by 480 pixels or 1280 by 960 pixels were displayed, only a part of the original image is displayed as the image-display screen on the VGA-based monitor, and the remaining portion of the original image will be discarded.
In order to eliminate the above problems, the conventional electronic album system must carry out the image data processing every time the image-display screen is changed from one to another during the image displaying procedure of FIG. 3, in order to display one of the album items, thumbnails or digital images in a proper manner. In particular, when a large amount of the original image data is stored in the hard disk, it is difficult for the conventional electronic album system to accomplish the image data processing for each screen change and display a selected image at any time. It is difficult for the conventional electronic album system to quickly display a selected image in response to the operator's action because the image data processing based on the original image data is time-consuming.